Animal lungs (90 mice and 30 hamster) exposed to vinyl chloride monomer by inhalation at low doses (1ppm, 10ppm and 100ppm) and for short durations of exposure (4 weeks), will be studied by gross anatomy, light microscopy and electron microscopy. Our objectives are (1) to study oncogenetic effects of vinyl chloride on mouse lung under these conditions and to observe processes of formation of the neoplastic cell from the precursor via the preneoplastic cell in the lung, on the level of ultrastructrue, (2) to characterize the non-neoplastic pulmonary damage by vinyl chloride in mouse and hamster, and to consider mechanisms underlying the damage, and (3) to evaluate vinyl chloride induced lesions in vinyl chloride workers' lungs.